Effects of a pharmaceutical mixture at environmentally relevant concentrations on the amphipod Gammarus fossarum

Abstract

The continuous discharge of pharmaceuticals into the environment results in the chronic exposure of aquatic organisms to complex drug mixtures. We examined the influence of a mixture of pharmaceuticals (carbamazepine (CBZ), diclofenac (DIC), metoprolol (MET) and 17a-ethinylestradiol (EE2)) at environmentally relevant (‘env’) and artificially high (‘high’) concentrations on Gammarus fossarum. Different sublethal responses such as moulting, reproduction and the content of the energy-storage component glycogen were analysed. The drug mixture influenced the moulting behaviour of gammarids at both the ‘env’ and ‘high’ concentration levels, leading to a discontinuous increase of body length in successive moults, compared with the constant increase of body length in the control treatment. Moreover, the time between successive moults of animals exposed to the ‘env’ and ‘high’ pharmaceutical concentrations was decreased because of shortened intermoult periods. We observed no significant impact of the pharmaceuticals on reproduction. In addition, the content of glycogen was not significantly affected by the drug mixture. Permanent exposure of G. fossarum to a wider range of pharmaceuticals in natural aquatic systems may influence moulting behaviour and accompanied life-history parameters, followed by severe ecological consequences as gammarids play an important role in many freshwater ecosystems of the northern hemisphere.